1. Technical Field
The present invention generally relates to contactor circuits. More specifically, to a method of providing electrical current to a contactor circuit having a power supply adaptable for use with several contactor coils having different electrical specifications.
2. Background of the Invention
Manufacturers are concerned with the cost of making products. Products may be redesigned so that they can be more easily made on existing equipment without the need for purchasing additional or special machinery. Similarly, manufacturers will attempt to design products having a single basic design with discrete elements that can be easily substituted or swapped.
Contactor circuits may include power supplies that are derived from the power existing within the coils of the contactor. The derived power supply is designed to provide a nominal current to the contactor.
Because the nominal current provided by a contactor coil may vary greatly depending upon the voltage of the coil being operated, a power supply circuit suitable for use with one coil may not be suitable for use with another coil having different electrical specifications i.e., voltage and current characteristics. For, example, a family of contactor coils having the same power specifications can have varying voltage and current specifications, thus, a lower voltage coil will require higher current to operate properly while a higher voltage coil requires less current.
Using a power supply circuit that provides excessive electrical current to the contactor circuit will stress the circuit""s components and adversely affect their performance and life span. Prior to this present invention, a need existed to reduce manufacturing costs of power supply circuits for contactor coils.
This invention is designed to resolve these and other problems.
A power supply circuit is capable of shunting excess current away from a contactor circuit over a wide range of contactor coils used to derive the power supplied to the contactor circuit. The power supply circuit enables a contactor designer to use the same circuit in several different operating voltages and supply currents by simply changing the value of the power supply resistor. Placing the power supply resistor external from the power supply circuit allows the manufacture of a single electronic board assembly, thus reducing manufacturing costs. The power supply resistor can be installed into the assembly near the end of the manufacturing process dependent upon the contactor coil to be used.
The first embodiment of the present invention is directed to a method for providing electrical current to a contactor circuit, the steps comprising: providing a contactor; providing a power supply circuit having a power supply resistor, the power supply circuit supplies electrical current to the contactor circuit in response to the electrical specifications of the contactor; selecting a value for the power supply resistor in response to the contactor""s electrical specifications and requirements of the contactor circuit; and inserting the selected power supply resistor into the power supply circuit.
Another embodiment of the present invention is directed to a method for providing current to a coil independent contactor circuit, the steps comprising: providing a contactor, the contactor having a holding coil; providing a power supply circuit having a power supply resistor, the power supply circuit supplies electrical current to the contactor circuit in response to the electrical current specification of the holding coil; selecting a power supply resistor in response to the holding coil""s electrical specifications and requirements of the contactor circuit; and, inserting the selected power supply resistor into the power supply circuit.
The invention enables a manufacturer of contactor circuits with the ability to use the same power supply circuit with several different coils having different operating voltages and supply currents by simply changing the value of the power supply resistor. Placing the power supply resistor external from the power supply circuit enables the manufacturer to make a single, basic electronic board assembly that can be easily adapted for use with a variety of contactor coils having different electrical specifications. Mass production of a power supply circuit capable of being used for a variety of contactor coils reduces manufacturing costs.